Instrument for inscribing an ellipse



April 9, 1963 K. A. BOWEN INSTRUMENT FOR INSCRIBING AN ELLIPSE Filed April 14, 1961 2 Sheets-Sheet 1 F IG. 2

lllllllllllllll INVEN TOR. K E RMI T A.

A TTORNE Y5 April 9, 1963 K. A. BOWEN INSTRUMENT FOR INSCRIBING AN ELLIPSE 2 Sheets-Sheet 2 Filed April 14, 1961 INVENTOR.

KERM/T A. BOWEN v BYM y.

ATTORNEYS lJni-ted rates Patent Filed Apr. 14, 1961, Ser. No. 103,939 10 Claims. (Cl. 33--30) The present invention relates to ellipsographs of the type which is provided for inscribing, selectively, ellipses of different major and minor axes.

The ellipsograph of the present invention includes a main frame having upright legs which are connected with one another by a yoke. The foot ends of these legs rest on the surface to be inscribed and preferably are in the form of pins for piercing, for example, the paper surface on which the ellipse is to be drawn; this yoke is provided with a longitudinally extending guideway and is arranged parallelly of the surface on which the ellipse is to be inscribed.

A second frame is mounted on the main frame for oscillatory movement relative to the main frame on an axis lying below and parallelly of the guideway of the yoke.

An upright or vertically extending shaft is journalled in the second mentioned frame and is disposed between the legs of the main frame. A horizontally extending arm is rotatable with the shaft and disposed between the second mentioned frame and the guideway of the yoke. This arm is provided with an element which cooperates with and is guided along the guideway. A second horizontally extending arm is rotatable with the shaft and is disposed below the second mentioned frame. A lever is pivotally attached to the free end of the lower arm and is movable vertically. An inscriber is carried by this lever.

The upper arm is provided with a guideway which is arranged parallelly with the guideway of the yoke. The element, which is guided by the yoke guideway, is guided by and selectively, adjustably fixed with respect to the arm guideway for selecting the lengths of the major axes of ellipses. The lever on the lower arm also is provided with a guideway which is arranged substantially parallelly with the guideway of the yoke. The inscriber is guided by and selectively, adjustably fixed with respect to the lever guideway for selecting the widths of the minor axes of the ellipses.

The advantages will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the invention is illustrated.

In the drawings:

FIG. 1 is a perspective View, in elevation, of the instrument;

FIG. 2 is a view, partly in section, the section being taken along line 2-2 of FIG. 1;

FIG. 3 is a side view of the main frame and showing the rotatable shaft, the arms, the lever and the inscriber displaced ninety degrees from that shown in FIG. 1;

FIG. 4 is a side view, partly in longitudinal section, of the main frame and showing the rotatable shaft, the arms, the lever and the inscriber displaced one hundred and eighty degrees from that shown in FIG. 3; and

FIG. 5 is a fragmentary view of the upper part of the instrument, showing parts in section.

The instrument 20 comprises a main frame 22 including upright legs 24 and 26, each having a foot in the form of an upright pin 28 and 30, respectively. The upper ends of these legs terminate, respectively, in sections of a circle 32 and 34 which are bridged at the top by a yoke 36.

Bearing means, having a horizontally disposed axis, is provided below the yoke and is herein shown as two hardened ball bearings 38 and 40'. These balls extend partly within aligned sockets 42 in each of the sections 32 and 34 of the legs. These sockets are formed by drilling through circular sections and providing hardened bearings 44, each having a hollow surface ground to the shape of the segment of a hollow sphere, confronting, receiving and complementing the ball bearings. These bearings 44 are held in adjusted position, with respect to the ball bearings by set screws 46. This bearing means carries a T-shaped frame 50 having cross arms 52 and 54 and a depending leg 56. Each of the extreme ends of the cross arms is provided with a socket 58 having a hollow surface ground to the shape of the segment of a hollow sphere, and confronts, receives and complements the ball bearing.

The depending leg 56 of the frame 59 is drilled longitudinally as at 60 on an axis disposed at right angles to the aligned axis of the ball bearings. A rotatable shaft 62 is journalled in the drilled hole 60 of the frame 50; thus the leg 56 provides a bearing for the vertically extending shaft 62.

The upper end of the shaft 62 carries a horizontally extending arm 64 which causes, in cooperation with a guideway 66 in yoke 36, oscillatory movement to be imparted to the frame 50 and shaft 62 when rotatable movement is imparted to the shaft. This oscillatory movement is about the horizontal axis of the aligned ball bearings 38 and 40.

The degree of such oscillatory movement is adjustable and may be selectively set. To accomplish this, the arm 64 includes a horizontally eXtcnding guideway in the form of a slot 68 forming a track for guiding a carriage 70. This carriage includes a side portion 72 which is slidable along one side of the arm 64 and an upper portion 74 which rides on the top of the arm. The side portion 72 is drilled and threaded for receiving a screw 76, the shank of which extends through the slot and the head causes the arm to be clamped between the head and the side portion 72. The top of the carriage 70 is provided with a hollow surface which complements and receives a ball bearing 80. The carriage is formed of a hardened metal and the ball is preferably formed of nylon. This ball is guided by the horizontally extending groove in the yoke 36, which groove has heretofore been termed the guideway 66. This groove 66 is arcuate in cross section and complements the ball; the slot or guideway 68 of arm 64 is disposed in a horizontal plane lying parallelly with and below the plane of groove 66.

As the shaft is turned, the ball 88 will follow the grooved guideway 66 in the yoke 36. This turning movement causes the lower end of the shaft 62 to swing outwardly, in one direction, during the first quarter turn of the shaft, when starting from the position shown in FIGS. 1 and 4; then on the next quarter turn, the lower end of the shaft will be moved inwardly; continuing the turning movement, the lower end of the shaft will be swung outwardly, in the opposite direction; upon completing the single three hundred and sixty degree turning of the shaft, the shaft will have returned to the original position. The lengths of the outward movements in opposite directions is governed by the length of the lever arm, ie by the horizontal length of the distance between the axis of shaft 62 and the point of contact of the ball in the groove 66. This length of lever arm and consequently the length of movement of the lower end of the shaft is selective by moving the carriage 7% various distances along the slot 68. The outward movements of the lower end of the shaft 62 is progressively increased by progressively moving the carriage outwardly. As previously stated, it is locked in the desired position by screw 76.

The lower end of the shaft carries an outwardly extending arm 84; it extends generally in the same direction as arm 64. The free end of arm 84 is bifurcated for receiving a lever 86 which is pivotally carried by the arm through a pivot pin 88. Lever 36 extends toward and beyond the axis of shaft 62.; the end of the lever is provided with feet 90 and 92, foot 92 being a roller. The lever is provided with a guideway 94 in the form of a slot 96- and a concentric countersunk groove $25, which latter receives a nut 1%. This guideway is substantially parallel with the surface 162, which is to be inscribed, and the guideways 66 and 63. A carriage lltld is carried along one side of the lever 86, and this carriage is fixedly secured in the desired position along the length of the guideway by a thumb screw 106 and the nut 1%. This carriage carries a vertically extending inscriber 168 in the form of a style, pen or pencil.

In operating the instrument 2%, the pins 28 and 3% are placed in longitudinal alignment with the major axis of the ellipse to be inscribed and the axis of the shaft 62 is disposed midway of the major and minor axes of the ellipse to be inscribed. At this time the frame is perfectly erect, i.e. the shaft 62 is aligned intermediate the legs 24 and 26. The carriage 164 is then adjusted horizontally so that upon one hundred and eighty degree movement of the shaft, the inscriber will contact the surface at the remotest points of the minor axis of the ellipse to be inscribed. After this is done, then the carriage 76 is adjusted horizontally for the desired length of the ellipse to be inscribed.

When the shaft 62 is being turned, the frame 22 is tilted gradually outwardly, about the pins 28 and 39, in the same outwardly directional movement of the lower arm 84 until the free end of the arm reaches its extreme outer position; then, as the arm is moved inwardly, the frame 22 is moved gradually to its vertical position. Upon continuous rotation of the shaft 62, the opposite tilting and retraction of the frame is necessary. FIG. 3 shows one extreme tilted position of the frame for a predetermined selected set position of the carriage '70, and FIG. 4 shows the other extreme and opposite tilting position of the frame with the same position of the carriage 7t).

The shaft 62 is conveniently turned by a knurled knob 11%) which is slidable vertically on the shaft. This knob is suitably connected with the lever 86 by a rod 112 and a tempered resilient biasing spring in the form of a rod 11 One end of the rod 112 is fixed to the knob lltl and the other end is fixed to one end of the spring rod 114. The other end of rod 11 is fixed to that end of the lever $6 which is pivoted to arm 84. The knob 11% and the pivoted end of the lever 86 are normally biased upward by a coil spring 116 which surrounds shaft 62 and which is interposed, under compression, between the top of arm 84. and the bottom of the knob. Under such bias condition, i.e. when actual inscribing is not being done, the inscriber is lifted off of the surface ltlZ. During the act of inscribing, downward pressure is applied tothe knob 110 to overcome the resistance of spring 116, forcing the pivoted end of the lever downward whereby the point of the inscriber ltlS rides on the surface 192 and inscribes the ellipse when the lever 86 is rotated. As previously stated, during inscribing, the frame must be tilted first one way and then the other about the pins 28 and 30. By providing the resilient rod 114 between rod 112 and the lever 86, the degree of accuracy of extent of tilting can be materially reduced.

Referring particularly to FIG. 5, it will be observed that arm 64 is provided with a downwardly extending skirt 118 arranged concentrically of the shaft 62. The skirt extends into a countersink 12% in the upper part of'frame Sit and which is also arranged concentrically of the shaft 62. A compressing spring 122 is interposed between the bottom of the countersink and the underside of arm 64. This spring'normally biases the arm 64 and the shaft, affixed thereto, upwardly so as to yieldingly retain the ball 80 in the groove 66.

By virtue of the present invention, perfect planar ellipses can be inscribed of various major and minor axes. The device may be readily actuated by one hand of the draftsman by merely rotating the knob 11% and simultaneously gradually tilting the upper end of the main frame outwardly, first in one direction and then in the opposite direction.

While the form of embodiment herein shown and described constitutes a preferred form, it is to be understood that other forms may be adopted falling within the scope of the claims that follow.

I claim:

1. An instrument for inscribing ellipses upon a surface, comprising in combination, a main frame having upright legs connected with one another by a yoke, the foot ends of said legs resting on the said surface, smd yoke having a longitudinally extending guideway arranged parallelly of the said surface; bearing means on the frame having an axis disposed parallelly of the guideway and disposed intermediate the guideway and the foot ends of said legs; a second frame pivotally carried by the bearing means; a vertically extending shaft journalled in said second frame, said shaft having an arm above the bearing means; means on the arm guided by the guideway, said shaft having an arm at the lower end thereof, said arms being rotatable with the shaft; a lever; means for pivoting the lever for vertical movement on the free end of the lower arm; and an inscriber carried by the lever.

2. An instrument as defined in claim 1, including means for biasing the lever upwardly; and means for forcing the lever downwardly.

3. An instrument as defined in claim 2, in which the means for forcing the lever downwardly includes a knob slidably vertical on the shaft; and means for connecting said knob with the lever.

4. An instrument as defined in claim 3, in which the means for connecting the knob with the lever comprises a resilient member.

5. An instrument as defined in claim 1, in which the said arms on the shaft are arranged substantially parallel of one another.

6. An instrument as defined in claim 1, in which the first mentioned arm on the lever is provided with a longitudinal guideway lying substantially parallel with and below the guideway of the yoke, and the means on the upper arm, which is guided by the guideway on the yoke, is adjustably fixable with respect to the guideway on said first mentioned arm.

7. An instrument as defined in claim 1, in which the lever is provided with a longitudinal guideway lying substantially parallel with the guideway of the yoke, said inscriber being adiustably fixable with respect to the guide way on the lever.

8. An instrument as defined in claim 1, in which the first mentioned arm on the shaft is provided With a longitudinal gniideway lying substantially parallel with and below the guideway of the yoke, and the means on the upper arm, which is guided by the guideway on the yoke, is adjustably fixable with respect to the guideway on said first mentioned arm, and in which the lever is provided with a longitudinal guideway lying substantially parallel with the guideway of the yoke, said inscriber being adjustably fixable with respect to the guide-way on the lever.

9. An instrument as defined in claim 1, including means between one of said frames and the first mentioned arm for normally yieldingly urging said first mentioned arm upwardly.

10. An instrument as defined in claim 1, including means on the second mentioned frame and the first mentioned arm for normally yieldingly urging said first mentioned arm upwardly.

No references cited. 

1. AN INSTRUMENT FOR INSCRIBING ELLIPSES UPON A SURFACE, COMPRISING IN COMBINATION, A MAIN FRAME HAVING UPRIGHT LEGS CONNECTED WITH ONE ANOTHER BY A YOKE, THE FOOT ENDS OF SAID LEGS RESTING ON THE SAID SURFACE, SAID YOKE HAVING A LONGITUDINALLY EXTENDING GUIDEWAY ARRANGED PARALLELLY OF THE SAID SURFACE; BEARING MEANS ON THE FRAME HAVING AN AXIS DISPOSED PARALLELLY OF THE GUIDEWAY AND DISPOSED INTERMEDIATE THE GUIDEWAY AND THE FOOT ENDS OF SAID LEGS; A SECOND FRAME PIVOTALLY CARRIED BY THE BEARING MEANS; A VERTICALLY EXTENDING SHAFT JOURNALLED IN SAID SECOND FRAME, SAID SHAFT HAVING AN ARM ABOVE THE BEARING MEANS; MEANS ON THE ARM GUIDED BY THE GUIDEWAY, SAID SHAFT HAVING AN ARM AT THE LOWER END THEREOF, SAID ARMS BEING ROTATABLE WITH THE SHAFT; A LEVER; MEANS FOR PIVOTING THE LEVER FOR VERTICAL MOVEMENT ON THE FREE END OF THE LOWER ARM; AND AN INSCRIBER CARRIED BY THE LEVER. 